If your doctor suspects you have arthritis, he or she may use a magnetic resonance imaging (MRI) test to diagnose your condition. An MRI uses radio waves and a magnetic field to obtain images of organs, tissues, and other structures in the body. Typically, the images from an MRI test are more detailed than other imaging tests, such as ultrasounds and x-rays.
There are two main types of arthritis: osteoarthritis (OA) and rheumatoid arthritis (RA). OA is caused by a breakdown in the protective tissue, called cartilage, that covers your joints. RA is an autoimmune disease that causes joint damage. Orthopedists, doctors who specialize in bone health, increasingly use MRIs to make a diagnosis of osteoarthritis. Doctors can also use these images to look for muscle and cartilage tears around joints.
How is an MRI used to diagnose osteoarthritis?
A radiologist may perform an MRI of a joint with possible osteoarthritis if X- rays are inconclusive. The doctor may also want to look for possible tears and strains in other tissues surrounding the joint.
During the visit, the MRI technician will ask you to lie on a table. He or she will then move the table into the MRI machine, so that the injured area is in the machine. This means that if your shoulder is being looked at, only the top half of your body will need to be in the machine. Your MRI results will then be sent to your doctor, who you’ll see at a follow-up appointment.
When examining an MRI, an orthopedist will typically look for the following structures, which may indicate osteoarthritis:
- damage to the cartilage
- osteophytes, also called bone spurs
- subchondral sclerosis, which is increased bone density or thickening in the subchondral layer of the joint
- joint effusion, or excess swelling of fluid around the joint
- synovitis, which refers to inflammation of the synovial membrane in joints
- tears in ligaments, which may increase your risk for early osteoarthritis, or cause pain or impaired function
What other methods are used to diagnose osteoarthritis?
Before scheduling an MRI, your doctor will first review your symptoms and ask:
- your degree of pain
- how long you’ve had pain
- activities that are difficult because of your pain or decreased mobility
Your doctor will also perform a physical examination and look for the following:
- swelling around your joint, which can be a sign of excess fluid
- thinning of the muscles
- reduced movement in the joint
- tenderness of the joint
- grating sounds when you move the joint, called crepitus
- swelling in the bone
- instability in the joint
In addition to your physical exam, there are common tests, including an MRI, that your doctor may request. These include:
- X-rays: Like MRIs, these images are also good at discovering common features of osteoarthritis including bony spurs, narrowing of the space between bones, and possible calcium deposits. X-rays are less expensive than MRIs, and the results are usually obtained more quickly.
- Blood tests: There is no blood test for osteoarthritis. However, your doctor may use it to rule out other possible diagnoses.
- Joint fluid analysis: If there is significant swelling around the joint, a doctor may use a needle to withdraw fluid and test the sample for possible gout, infection, or osteoarthritic-related inflammation.
Your doctor may also look at your medical history and see if you have risk factors for osteoarthritis including obesity, age, smoking, and family history.
Causes of and risk factors for osteoarthritis »
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